Therapeutic preparations of iron



United States A Patent THERAPEUTIC PREPARATIONS OF IRON Eric London, Fareham, Hampshire, and George Daniel Twigg, Goostrey, Cheshire, England, assignors to Benger Laboratories Limited, Holmes Chapel, England, a British company No Drawing. Original No. 2,820,740, dated January 21,

1958, Serial No. 412,405, February 24, 1954. Application for reissue September 22, 1958, Serial No. 765,693

Claims priority, application Great Britain February 27, 1953 12 Claims. (Cl. 167-68) Matter enclosed in heavy brackets appears in the ori innl patent but forms no part of this reissue specifica on; matter printed in italics indicates the additions made by reissue.

This invention relates to the manufacture of colloidal therapeutic preparations containing iron suitable for use in parenteral injection and of the type called generically colloidal injectable iron preparation.

It is well-known that the so-called saccharated oxide of iron preparations can be used for injection purposes in the treatment of iron-deficiency anaemia. These preparations consist essentially of aqueous solutions containing ferric hydroxide in colloidal form and stabilised by the presence of sugars (especially sucrose), of sugar mixtures, optionally modified by a preliminary heat-treatment, the components being admixed in the presence of a suitable alkali.

While such materials may be injected intravenously without toxic effects, they are found to be disadvantageous for intramuscular or subcutaneous injection, since, owing to the high osmotic pressure and the possible alkalinity of this type of solution, intramuscular injection usually results in considerable pain and inflammation at the site of the injection, even when sub-therapeutic doses are administered. The unsuitability of such products for intramuscular injection is rendered even more obvious by the fact that they are not absorbed appreciably when iniected by this route.

It is considered desirable for an iron solution intended for intramuscular injection to be able to satisfy the following requirements:

(a) No effect of the pH of the body fluids; (b) Isotonicity with' the tissue fluid; (c). Stability in presence of protein and electrolytes; (d) Ready availability for haemoglobin synthesis; j (e) Rapid absorption coupled with a low rate of ex :retion;

(f) Maximal iron content in minimal volume, i.e. 3 to i% elemental iron in solution; (g) Low toxicity; 1 (h) Reproducibility;

(i) Stability on storage.

The principal object of our invention is to provide more particularly for the treatment of iron-deficiency naemia a colloidal iron preparation, which is especially uitable for intramuscular injection (although adaptable lso for intravenous use) and is well-tolerated without me onset of undesirable local or general side-effects. A urther object is to obtain an iron-containing colloid, esentially free from iron ions, which can be administered 1 dosage adequate for producing the required therapeutic :sponse and from which the iron is absorbed rapidly into 1e circulation with absence of untoward'systemic reacons, 'e.g. vasodilation, headache, lumbar pain, vomiting nd loss of consciousness.

With the foregoing objects in view, the present invention provides a therapeutically effective iron preparation consisting essentially of-a colloidal substantially non-ionic ferric hydroxide-partially depolymerized dextran complex, believed to be novel in itself. A colloidal iron preparation may be produced according to the invention by reacting, with such heating as may be necessary, a solution of a partially depolymerized dextran, a solution of suspension of a ferric compound (which expression covers for example the ferric compounds hereinafter specified or a mixture of ferric compounds), together with alkali, to form a colloidal solution from which any undissolved matter may be separated and whose pH is or, if necessary, is adjusted to between 4.0 and 11.0 within which range the preparation appears to be capable of retaining its stability in water for reasonable periods of time. However, the pH of the preparation for injection may be, or if necessary, maybe adjusted to between 5.5 and 8.5 and preferably 6.5.

In carrying out this method, the partially depolymerized dextran may either be dissolved in the solution or suspension of the ferric compound with subsequent addition of the alkali, or alternatively, the dextran can be dissolved in the alkali, to which the ferric compound in solution or suspension is then added.

Though the molecular structure of the product is not yet known with certainty, and it can therefore be defined only in empirical terms, our parenteral iron preparation may possibly consist of an aqueous solution of colloidal ferric hydroxide complexed with enough of the partially depolymerized dextranto stabilise the solution satisfactorily for the purpose of injection but not so much ferric hydroxide as to require an excess of the dextran over the requirements of such injection in other respects, e.g. as regards the consistency of the solution. If the iron content is excessive, the amount of the dextran needed to stabilise it is so great that the resultant high viscosity of the product renders it unsuitable for use as a parenteral iron preparation and a minimum dextramiron ratio exists below which the iron can no longer be stabilised so as to be suitable for an injection- The partially-depolymerized dextran which we use as a starting-material isderived from raw dextran obtained according to known methods by growing under carefullycontrolled conditions of temperature, appropriate organisms, especially Leuconostoc mesenteroides, syn. Betacoccus arabinosaceous in a suitable nutrient medium containing a high proportion of sucrose. It is further known that the highly polymerised raw dextran gives rise on partial degradation as, for example, by treatment with dilute mineral acid, to simpler polymeric forms from aqueous solutions of which (being polydisperse), fractions of different average molecular weight can be precipitated by adding a suitable water-miscible organic liquid, such as methyl alcohol, ethyl alcohol or acetone. These degradation products consist of polymerised glu- :cose residues, joined predominantly by a-1:6 and, to

j dextran itself, which are here of secondary importance.

In the present context the intended meaning of intrinsic viscosity is the limiting value of specific viscosity divided by concentration at infinite dilution measured bythe following-method. The flow time of at least three solu firms Q difier nt on entrations.(.a1l.1ess;than,5,%, w.l,v. dextran) is determined in an Ostwald viscometer. The flow time of the solution divided by the flow time for water at the same temperature, gives. therrelativoviscosity of the dextran solution at thegivenqconcentrationt The specific. viscosity oi a dextransolutionlat aagiven concentration, is. obtained, by subtracting 1.03 from the. value. for relativeviscosity. For each concentration; oft dextran solutionthefactor (specificviscosity divided by'concen: tration) is. calculated and this, factor is: plotted: against thepercentage concentration of the solution-iron; which it. obtained; By extrapolating; the, graphobtained to zero concentration, the: limiting valuev of the factor: (spew viscosity dividedby concentration); is, obtained; Thi value is known s he intrinsic; vi cosity ofrthei mar. terial insolutionr Due to the fact: that therfractionsrof de randescribed are polydisperset. the: term averageiim trinsic viscosity is used.

c void any-p s ibl misinterprctationrthetermfaven intr nsic viscosi y? refers. to the; d xtran' itself; and not to: n aqueous: solution. of. dezttraluv an aqueous solution of the ferric hydroxide dextrazn': complex.

Wehave found. that stable iron: solutions: can be pr paredfrornfractions of dextranof intrinsicwviscositwrang ing.;,f rom1 0.025 to 0.5; but thequantity; of; iron; stabilised" per, unit, weight, of, dextran decreases as i the, intrinsic visteosityofi the dextra-n colloid increases. The;- iron content. of a solution considered; to 17.6.5; adequate:- for, parenteral. injection is atleast 2% and-our investigationsgzhaveshmvn the I in order to obtain a stablepreparation:whi-chpossesse escl nical utility the 'dextran selected: asa startingemateriai must have an upper limit. ofv intrinsic viscositywhich does not; appreciably exceed 0.2 and: which more particularly has;an intrinsic viscosity inthe; range from about-0.025 toabout-Oli .at;25 C., A therapeutically-useful:preparas tioncontainingfromB to 5% elementaliron (correspond? ing to, from 6,to= ferric hydroxide.) canbe-obtainedfrom a-.-fractionated. dextran with an intrinsicsviseosity of (1.03:, to 0116:, when thepartially depolyrnerized v dextrarr content is approximately 3Q to 5.0%..

Thctcolloidal ferric; hydroxide mayzsbesformed' in-pre'sa ence of the partially dcpolymerized dextranby heatinga asuitable water-soluble ferric; salt and the dextrantoxgether in aqueous solution with. excess: of alkali;

Suitable ferric compounds comprises (.i); water soluble ferriesalts suchas the chloride, nitrate, sulphateor acetate: and double. salts suchas ferric ammonium sulphate; on their obvious chemical equivalents; (ii). ferric:oxy-sa'lts; prepared by dissolving. ferric hydroxide in" a: solutionof: a=.fcrric salt; dialysed iron solution B' .P;C. and freshly precipitated washed ferric hydroxide; (iii).'any ferricz:com--' pound which, whenrendered' alkaline in the:- presence of dextran, gives rise to ferric hydroxide.

The alkali of choice for thepurposeof this inventiom is. sodium hydroxide, but: other suitable: al-k'alis=- comprisethe-hydroxides of lithium, potassium-and arnmoniumy the carbonates of lithium, sodiumand potassium andi thein obvioustchemical' equiyalentsi.

Stable. preparations appropriate-for intramuscular" ins jectionrcan also be obtained-accordingto, ouninvention from ferric citrate, ferric ammonium: citratetandzferric: glycerophosphate, but in: these instances :wehaveishown. it to;-be-- desirable definitely to use a: caustic ,alka1i ,.,for*ex.-.-

ample,, sodium hydroxide, as-the agent.forrenderinggthe mixture alkaline during-the preparation, thereof,

W h ve f rther-found thatrour novel colloidal iniee -r le iron prepara ions. can, e..,-puri.fi d from-the electroelytes-qwhich are, formed simultaneously asgby-productsrby, utilising either of, the following techniques (i) Subj'ecting a preparation according to the invention. to dialysis against running wateruntil the desired'osmotic pressure hasbeen obtained; Q

(ii)" Mixing a preparation. according to the invention: with a suitable waterrmiscible" solvent such as: methyli alcohol; ethyl alcohohor aeetone in quantity sufieint under theregisteredtrademark cellophane.

4' separate, the..col1oid,. separating the latter from solution and re-dissolving it in distilled water to the required concentration.

It sometimes happens thatca parenteral iron preparation obtained by, the improved processis slightly hypotonic; thus the freezing-point depression of a colloidal solution containingabout 5% elemental iron, as normally prepared for-intramuscular injectiomisfrequently lcss'than (153 C. (the approximate depression obtained withisotonic saline): in such a case, a suitable amount of'an appro priate, substance such as: sodiumchloric or glucose:- may beadded to raise the freezing-point depression value; of thepreparation to 0',53- C- and"; thereby render; it: substantially isotonic with blood.

if the pHof a colloidal iron preparation in accordance with our invention fallsoutside the range 5.5 to 8.5, there can be added, prior to sterilization, sufficient acid or alkali, as the casemay-be, to ensure that a pH value falling within theselimits,- and preferably 6.5, is finally attained; for. clinical use.

Sterilization. of. the, preparations, made in accordance with the present invention can be efiected by autoclayiug the said preparations in their final containers, as, forexample, ampoules; for 30 minutes ata steam pressure of lfi lbs; per square'inch; corresponding-to a temperature of'llS- C. I

When colloidal solutions prepared in accordance with our-inventionaredehydrated as, for example, by evaporation underreduced pressure or, alternatively, by' the s'epa'e ration and-subsequent desiccation of, the product obtained on' precipitating the colloid'by' adding a suitable waters miscible-solvent'such as methyl alcohol, ethyl alcohol or acetone, there can be obtainedsolidified preparations suit-; able fortheimmediate reconstitution of colloidalflinjectable iron solutions by the addition of distilled water.

Tested for intravenous toxicity in mice, a preparation obtained according to our investigation may show an liDg value in excess of600*mg./kilo: this result compares most favourably'withi a, commercialsaccharated oxide of iron preparation. whi cln when tested under similar conditions', indicated an LD5 of 300 mg./kilo.

On injecting a colloidal parenteral iron. preparation made. in accordance with. this invention intov mice by, the intramuscular route it has not" been. found possible to administer a,dosage' suificiently large to kill any of'tlie" test animals (mice or rats) using the highest practical intr'ak muscular dosage of the material, viz: 5 ml'sJkilo. orresponding to 250" rngms. Fe/kilo.).

The following are examples by way of illustration only; of preparations in detail according to the invention.

EXAMPLE 1- To 25 g. partially-depolymerized dextran (intrinsic'sviscosity: 0.07)), dissolved in: water. (50 ml'.), was; added sodium hydroxide (15 g.) in water (25 ml.), followedby 40. ml. of,30% w./,v. aqueous ferric. chloride. The mixture was heated to boiling for'about 15 ,minutesand al lowed to cool to room temperature. Thesolidthat-Jemained undissolved was then removedfby centrifugafi'on and the solution dialysed against running waterfon approximately 24 hrs., using tubing madeof material known The'dialy sed solution wasconcentrated under reduced'pressure to yield a;-clear,,stabl'e solution containingthe equivalent of4'.15%'1 elementalgiron. Theproudct was again filterediandfst'eri-i. lised by autoclavingtat.a.steam;pressureeof; 1.0Tlbs.', per; square inch 01530 minutes, its final pH- value. being .,6.8lz The preparation was found to'have-a freezingvpointidee pressionqofi: (L18? C.,-, compared with; pure water; which on: addition of 06% w-./v. aqueous sodium: chloride; was: raised to;0.6.0',* C.

material' wh'en tested for" intravenous toxicityrin: mice gave an LD value of approximately"800 mgilldlos EXAMPLE 2 To 25 g. partially-depolymerised dextran (intrinsic viscosity: 0.05) dissolved in water (50 ml.) was added sodium hydroxide (15 g.) in water (25 ml.), followed by ferric citrate (22 g.) in water (200 ml.). The mixture was heated for approximately 2 hrs. at 65 C., with stirring and the resultant dark red solution was filtered and cooled. The filtrate was stirred with 95% ethyl alcohol and the treacly precipitate separated, prior to its being redissolved in about 1 litre distilled water. From this aqueous solution, the material was again precipitated under the same conditions, to be once more dissolved in distilled water. The filtered aqueous solution was evaporated under reduced pressure at 45 C., until the solution contained 5% Fe, as determined by assay.

EXAMPLE 3 400 g. of dextran having an intrinsic viscosity of 0.04, and 103 g. of anhydrous sodium carbonate are dissolved in 800 ml. of hot water. This solution is cooled and to it 400 ml. of a solution of ferric chloride (containing 100 g. FeCl is added with stirring. After the liberated carbon dioxide has escaped, the resulting solution containing colloidal ferric hydroxide stabilized with dextran and also sodium chloride produced during the reaction, is dialysed against water, using, for example, cellophane as a membrane. When its sodium chloride concentration has in this way been reduced to about 0.2%, the solution is concentrated under atmospheric pressure until the volume is reduced to about 600 ml. The preparation is then adjusted to a 5% content of iron and sterilized by autoclaving in the final containers.

We claim:

1. A composition comprising a substantially nonionic complex of ferric hydroxide with a dextran having an average intrinsic viscosity at 25 C. of about 0.025 to about 0.25, said complex being stable in contact with water.

2., A therapeutic composition comprising a stable aqueous solution of a substantially non-ionic complex of ferric hydroxide with a dextran having an average intrinsic viscosity at 25 C. of about 0.025 to about 0.25.

3. A composition comprising a substantially non-ionic complex of ferric hydroxide with a dextran having an average intrinsic viscosity at 25 C. of about 0.03 to 0.06, said complex being stable in contact with water.

4. A therapeutic composition for treating iron deficiency anemia comprising a non-toxic, sterile, colloidal aqueous solution of a substantially non-ionic complex of ferric hydroxide with a dextran having an average intrinsic viscosity at 25 C. of about 0.025 to about 0.25, said solution having a pH of about 4 to about 8.5.

5. A composition according to claim 4 having at least 2% elemental iron.

6. The process which comprises parenterally administering to an animal a therapeutic amount of a substantially non-ionic complex of ferric hydroxide with a dextran having an average intrinsic viscosity at 25 C. of about 0.025 to about 0.25.

7. The process of claim 6 in which the parenteral administration is intramuscular.

8. The process of preparing a. substantially non-ionic colloidal ferric hydroxide-dextran complex which comprises combining, in contact with water, a dextran having an average intrinsic viscosity at 25 C. of about 0.025 to about 0.25 with ferric hydroxide, said ferric hydroxide being formed in situ in contact with the dextran by a double decomposition reaction between an ionizable ferric salt and an alkali base.

9. The process of claim 8 in which the resulting ferric hydroxide-dextran complex in water is dialyzed to remove electrolytes.

10. The process of claim 8 in which the pH is adjusted to the range from about 4 to about 8.5.

11. The process of claim 8 in which the resulting ferric hydroxide-dextran complex is purified by precipitation with a water miscible solvent, the precipitate is separated, and redissolved in water.

12. A composition comprising a substantially nonionic complex of ferric hydroxide with a dextran having an average intrinsic viscosity at 25 C. of about 0.03 to 0.06, said complex containing at least 2% elemental iron, and being stable in contact with water.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS 2,518,135 Gaver Aug. 8, 1950 2,572,923 Gaver Oct. 30, 1951 2,609,368 Gaver Sept. 2, 1952 OTHER REFERENCES Zief et al., J.A.C.S., 2126-7, Apr. 20, 1952. Manufg. Chem., 23:2, February 1952, pp. 49-54. Physician's Bulletin, May 1952, pp. 41-44. 

